Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Long-term Purchase Commitment [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 7,523
Operating Leases, Future Minimum Payments, Due in Two Years	7,037
Operating Leases, Future Minimum Payments, Due in Three Years	7,032
Operating Leases, Future Minimum Payments, Due in Four Years	6,866
Operating Leases, Future Minimum Payments, Due in Five Years	6,869
Operating Leases, Future Minimum Payments, Due Thereafter	41,769
Operating Leases, Future Minimum Payments Due	77,096
Operating Leases, Rent Expense	8,500	$ 8,900	$ 8,000
Site Service Commitments
Long-term Purchase Commitment [Line Items]
Site Service Agreements, Future Minimum Payments Due, Current Year	5,132
Site Service Agreements, Future Minimum Payments, Due in Two Years	5,132
Site Service Agreements, Future Minimum Payments, Due in Three Years	5,132
Site Service Agreements, Future Minimum Payments, Due in Four Years	5,132
Site Service Agreements, Future Minimum Payments, Due in Five Years	5,132
Site Service Agreements, Future Minimum Payments, Due Thereafter	223,312
Site Service Agreements, Future Minimum Payments Due	$ 248,972